Temperature-indicating instrument.



A. N. OZIAS, DECD. n. v. L. HAXBY L D. L.1AI110HILD, ADMINISTRATORS. TEMPERATURE INDICATING INSTRUMENT. APPLIoATIoN FILED 001.27. 1911.

Patented sept. 10,1912. 17(50. Z

Mimmo wz/XW UNITED STATES PATENT OFFICE.

ALBERT N. OZIAS, OF MINNEAPOLIS, MINNESOTA; R. 'V'. L. HAXBY AND D. L. FAIR- CHILD, BOTH OF HENNEPIN COUNTY, MINNESOTA, ADMINISTRATORS OF OZIAS, DECEASED.

SAID

TEMPERATURE-INDICATING INSTRUMENT.

Specification of Letters Patent.

Patented Sept. 10, 1912.

l To all whom t may concern.'

Be it known that I, ALBERT N. Oznis, a citizen of the Unitedy States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have vinvented certain new and useful Improvements in Temperature- Indicating Instruments; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawing, forming part of this specification, and to the figures and letters of reference marked thereon.

This invention relates to instruments in which variations in temperature will cause an indicationor perform mechanical func-k tions for the purpose of indicating or controlling temperature conditions or for compensating for variations in condition produced by changes in temperature.

The invention depends for its operation upon the differential expansion of metallic elements, one. of the objects being to provide a construction and arrangement of the parts whereby an increased movement of the indieating or cont-rolling devices may be produced by a given change in temperature without increasing the length of the memb ers having different coeliicie'nts of expansion.

Another object of the invention is to provide a device of exceedingly simple construction which may be housed in a casing of small compass and preferably of circular contour and which will embody in its oonstruction a minimum number of independent elements.

The invention primarily consists in an instrument which is actuated by the differential expansion of metallic elements under the inuence of changes in temperature and wherein the movement caused by `the diiferential expansion of the metallic elements yis augmented by a relative transverse displacement of the intermediate portions of arc members, one or both of whlch are changed in curvature by variations in temperature.

The invention further consists in certain novel details of construction and combinations and arrangements of parts all as will be hereinafter' described and ointed out particularly in the appended claims. Y

Referring to the accompanying drawings,--I"igure l is a front elevation of a thermometer embodying the present improvements; Fig. 2 is a view of the same instrument with the dial removed; Fig. 3 is a section on the line 3-8 of Fig. 2; Fig. 4 is an edge elevation showing the rack bar and pinion for translatingthe movement of the arc members into an angular movement of the indicating hand.

Like letters of reference in the several figures indicate the same parts.

In the embodiment of the invention illustrated in the accompanying drawings,

(which it will be understood is simply typical, inasmuch as the invention may be used 1n any form of controlling instrument or apparatus wherein movement must be effected by changes in temperature or the effect ofchanges in temperature upon movable parts neutralized) the working parts are mounted in a casing which conveniently consists of a cup member A secured upon a base plate B and having a transparent or glazed cover C. Within the casing there is a dial or face plate D having graduations or indications thereon with which av pointer E is adapted to register. The casing is conveniently made circular in form whereby it may be readily placed in position in 0r on an oven door, for instance, with a minimum of trouble and eX ense.

Within the casing there is fastened by a suitable screw or otherwise a plate F conveniently of segmental shape, or with two of its edges converging to a point where they meet a transversely extending arcshaped member G. The plate F and the arc-shaped member G are conveniently stamped up from sheet metal and preferably of metal having a high (2o-efficient of expansion, such, for instance, as brass. The arc-shaped member G has rigidly attached to one of its faces, preferably the convex face, a strip of metal H having a low coecient of expansion, such, for instance, as steel, or it might be of nvar. The connection between the two metals is usually formed by a series of rivets h, 7L, thus form` ing a bi-metallic thermostatic bar which is curved from end to end and the curvature of which will vary in accordance with changes of temperature, a higher temperature causing the curvature of the arc-shaped thermostat to lessen, while the lower temperature increases the curvature inthe well understood manner. To each endof the bimetallic arc-shaped members there is attached rigidly the ends of a member I, said member I, however, being ilexible and having a low co-eiicient of expansion, whereby any changes inthe curvature. of the bi-metallic member will vary the ydistance between the two arc members at` the center line, the relative movementJ at this point being much greater thanthe actual movement of the ends of the arc members, as will be readily understood. Centrally of the arc memberI there is attached a rack bar K with which a` pinion lc on an arbor c is adapted to mesh.v Said arbor' projects through the faceplate of the instrument and is adapted for the reception of theindicator or 'pointer E. 'The rack K is preferably of the conformation illustrated in Fig. 2, that is to say, it is provided with a hook-shaped head or end M adapted to pass through an aperture in the arc member I whereby .it will be held in engagement therewith, and with a nger or tooth N for the reception ofy one end of a light -coil is secured to an upturned finger o`r bracket P 'on the plate F.. The projection of the with the pinion, extends in a direction substantially parallel with the spring and the arrangement is such that the spring norvmally tends to hold the teeth of the rack bar .in engagement with the teeth of the pinion with a light pressure sufficient to maintain the operative engagement without lost motion between the parts, but without creating suiiicient pressure to interfere with the effective operation of the device.

the eXible-member is to change the stress in the same and while the spring O may serve as a means for detlecting the exible member, it is not eential as the stress (tension or compression) of the flexible member will be increased or decreased by the bimetallic member, regardless of the employment of the spring, and said flexible member will be deflected or resist deflection more or less, as the case may be.

With an instrument as thus constructedit will be noted that the available movement caused by a change in temperature is many times greater than the movement of the ends of the arc members, due to the fact that the transverse movement caused by the straightening out or the decrease in the curvature of both of the arcmembers is uti-v lized. .The range of movement -thus secured,

ably to an exceedingly compact arrangement of the mechanism as all of the operating parts may, as illustrated in the drawing, be mounted in -a small circular casing, and at the same time the construction and arrangement is such that the parts may be made in quantities.at small expense and when assembled will req'uire comparatively little separate adjustment in order to operate with accuracy. Furthermore t-lie structure lends .itself very favorably to the construction of thermometers adapted to indicate high temperatures, oven thermometers, for instance, although its usefulness is by no means limited to this particular field, as the essential elements, to wit: the bi-metallic arc 'member, the curvature of which is changed by `variations in temperature, and the defiectable member rigidly attached at its opposite ends to the o posite ends of the arc member, may be utilized in an infinite va- .iiety of instruments and mechanisms designed to indicate or control. temperature lconditions or to neutralize the effect of `va- 'riations in temperature. spring O, the opposite end of which spring 1 Having thus described my invention,

what I claim as new and desire to secure by 1Letters Patent of the United States, is rack bar carrying the teeth for engagement 1. In a device of the character set forth,

the combination with a curved bi-metallc tarc member, the curvature of which is ydelectable member at a point intermediate :the ends of the latter. The action of the bi.metallic member on 2. In a device'of the .character set forth,

:the combination with a curved bi-metallic arc member, the curvature of which' is changed by variations in temperature, of a deiiectable arc member attached rigidly at its opposite `ends to the opposite ends of -the bi-metallic arc member, and yielding means for utilizing the variations in such [deflection effected by the change in curvature of the bi-metallic member.

8. In a device of the character set forth,

`the combination with a curved bi-metallic :aspring connected with the flexible member intermediate the ends of the latter and lcontrolled by the changes in curvature of the two members due to kvariations in temperature.

4. In a device of the character set forth, the combination with a `curved bi-metallic arc member, the curvature of which is Achanged by variations in temperature, 4and a support connected therewith, of a flexible member attached rigidly at its opposite ends to the opposite ends of the bi-metallic member, actuated mechanism mounted on the said support and -connected With the HeXible member at a ends of the latter.

5. ln a device ofthe character set forth, the combination with a curved bi-metallic arc member, lthe curvature of which is changed by variations in temperature, of a Hexible member att-ached rigidly at its opposite ends to the opposite ends of the bimetallic member, and deflected centrally away from the bi-metallic member, and mechanism. actuated by the changes in curvature of the bi-metallic and flexible members under the inuence of variations in temperature.

6. ln a device of the character set forth, the combination With a curved bi-metallic arc member, the curvature ofY which is changed by variations in temperature, an oppositely curved arc member attached rigidly at its opposite ends to o posite ends of the bi-metallic member, an mechanism actuated by the changes in curvature of the two arc members due to variations in temperature.

7. ln a metallic thermometer, the combination with a base plate, an indicator journaled on said base plate and a bimetallic arc member connected with the hase plate at one side of the indicator, of a Hexible are member rigidly attached at its opposite ends to opposite ends of the bimetallic member, a. rack bar connected -with the intermediate portion of the eXible arc member for operating the indicator, and a spring for maintaining the parts under telision in one direction, substantially as described.

point intermediate the bination with a base plate formed of metal rhavinga high co-efflcient; of expansion and provided at one end with a curved arc member, a plate of metal having a low co-eicient of expansion rigidly attached tothe convex face of said curved arc member, and an indicator journaled on the plate, of a flexible arc member having its opposite ends rigidly attachedto the opposite ends ofthe first mentioned arc member, a rack bar connected with the intermediate portion of the iexible member, and `a tension spring connected at one end with a rack bar and at its opposite end with the base plate.

9. The combination With a curved bimetallic member, of a flexible member Aattached at its opposite ends to the opposite ends of the curved bi-metallic member, whereby the stress in the flexiblemember is changed by the action of the bi-metallic member under the influence of variations in temperature and mechanism to be controlled connected with the flexible member intermediate its ends.

v,10. The combination With a curved bi-l metallic arc member, the curvature of which is changed by variations in temperature, of

a flexible normally deflected arc member at ALBERT N. ozms. v

Witnesses:

ELLEN LAnsoN, L. A HULACLUK. 

